Optical ranging and target detection have become an important capability for imaging systems, offering 3D reconstruction of standoff targets and enabling tasks such as, target identification, characterization and orientation. Optical ranging and target detection may be performed by laser or radar. Typically, laser ranging is performed using a short pulsed laser, and a high-speed photodetector, measuring time of flight of the optical pulse and then calculating the distance to the target, given the speed of optical pulse (light).
However, modern radar systems are susceptible to jamming techniques capable of “spoofing” the transmitted radar signals, before they are received back. Classical electromagnetic (EM) radiation can be measured, copied and modified (spoofed), unbeknownst to the receiver. For example, a digital RF (radio frequency) Memory (DRFM) may be used to spoof or jam a radar (return) signal. A DRFM is an electronic method for digitally capturing and retransmitting RF signal. DRFMs are typically used in radar jamming, among other applications. A typical DRFM system digitizes an incoming RF input signal at a given frequency and bandwidth to adequately represent the signal, and then reconstructs that RF signal when required. The most significant aspect of DRFM is that as a digital “duplicate” of the received signal, it is coherent with the source of the received signal. More relevantly, a DRFM may modify the signal before retransmitting it. This modification can alter the signature of a target by adjusting its apparent radar cross section, range, velocity, and/or angle. Accordingly, DRFMs present a significant obstacle for radar sensors.
Techniques in pulse shaping of classical radiation have typically been used to try to defeat DRFM, however, these techniques merely make it difficult for a target to spoof a radar or laser detection and ranging (ladar) signal and thus do not provide for the physical impossibility of spoofing.
The present invention capitalizes on the no-cloning theorem and the properties of quantum entanglement of quantum mechanics to detect any spoofing or jamming of a radar/ladar system.